There is a risk in utilizing global position system (GPS) signals for detecting location and/or speed of travel. GPS signals can be spoofed using a malicious pseudolite. A pseudolite is pseudo-satellite which simulates a timing signal (carrier, C/A clock, and/or ephemeris). An erroneous pseudolite provides a signal that is delayed or advanced from a real GPS signal.
Another risk in utilizing GPS signals for detecting location and/or speed of travel involves damaged GPS signal transmitters. GPS satellites may malfunction, be damaged in orbit, deteriorate, or otherwise transmit inaccurate information. Examples of timing signals inaccuracies include signal delay due to atmospheric conditions, signal multi-path, orbital errors (e.g., inaccurate ephemeris data regarding a satellite's reported location), etc.
A prior art GPS receiver will compute an incorrect position if it receives data from an erroneous pseudolite or damaged GPS satellite since the GPS receiver will rely on the delayed or advanced GPS timing signal. Similarly a GPS receiver will rely on inaccurate timing signals due to the external conditions noted above. The GPS receiver will think that its position is further or closer to the source it is measuring. Based on the erroneous input, a prior art GPS receiver will compute a position that is moving at a rate that is different from the actual movement. Therefore, based on the erroneous data, a prior art GPS receiver's measurements will indicate that the GPS system is moving at a faster or slower rate, or moving on a different course, than in reality.
The potential inaccuracies can be risky when GPS systems are used for providing routing. It is more dangerous for self-guided vehicles and navigation systems.